currently I'm facing the following problem and I would be very glad, if anyone could help:from the following list ((a b c) (a b c) (a b) (a b) (a) (a)) I want to remove all duplicates, except (a b c). The result should be the list ((a b c) (a b c) (a b) (a)).As this function should operate on the first list, irrespective of the number of (a b c), (a b) or (a).I tried the function "remove-duplicates", but I don't know how to adapt it so that (a b c) duplicates are not removed.